Unsure of how to setup this "option"

Hey,
For he plugin I'm working on, currently each usergroup can only interact with 1 other usergroup and that group is set through a permission for that usergroup
So when your setting permissions for a Usergroup, you can either set "0" to interact with all other usergroups or an ID to interact with a specific usergroup.
What I would like is to be able to setup an option that would let me make a usergroup selector for each usergroup
So for example:

Administrative: [X]Administrative
[ ]Moderator
[X]Registered

Moderator: [ ]Administrative
[ ]Moderator
[X]Registered

Registered: [ ]Administrative
[ ]Moderator
[ ]Registered

So from the example above, Administrative can interact with Administrative and Registered
Moderator can interact with only Registered
Registered cannot interact with any groups

I've coded the above with a php callback
The problem i'm running into is the Array sub-options
Ideally i'd like the sub options to be the usergroup IDs

Any suggestions on how to do this or any other approaches that would work?